Epstein-Barr virus (EBV) is a human pathogen associated with a variety of cancers, including B cell lymphomas and nasopharyngeal carcinoma. EBV encodes an oncoprotein called the latent membrane protein-1 (LMP-1) whose activity is critical for B cell transformation by EBV. The ultimate goal of the proposed research is to explore the molecular and biochemical mechanisms by which LMP-1 contributes to EBV's life cycle in vitro and then to apply results to LMP-I's potential contribution to EBV's life cycle in vivo as it relates not only to the process of tumorigenesis but to the activity of EBV in latently infected B cells of healthy individuals. LMP-1 is expressed in infected primary B cells, immortalizaed lypmphoblastoid cell lines, and in some tumor cell lines or biopsies. LMP-1 functions as a constitutively-active cell surface receptor and activates positive growth- regulatory signals via its intracellular C-terminal signaling domain and negative growth-regulatory signals via its transmembrane domain. The studies described in this proposal are designed with the combined goals of understanding the function of LMP-I's hydrophobic transmembrane domain in the context of a) the mechanism of LMP-I's constitutive activation of cellular growth-regulatory signaling and b) signaling resulting in negative growth-regulation. Defining the mechanism of LMP- l's constitutive activation will provide insights into the control of cellular signal transduction and may be generally applicable to the molecular mechanisms involved in normal B cell growth control and in the aberrant growth of virally and nonvirally induced malignancies. Understanding the process of negative growth-regulation by LMP-1 will provide insights into the broad areas of cell cycle regulation and cytokinesis, and may shed light on the contribution of LMP-1 to EBV's life cycle in vivo, in transformed cells and in latently infected cells in healthy seropositive individuals. _ERP(JRMANGE S_TP--{S) {organization, city, state) >Department of Molecular, Cellular and Developmental Biology (MCDB), University of Colorado, Boulder KEY PERSONNEL. See instructions on Page 11. Use continuation pages as needed to provide the required information in the format shown below. Name Organization Role on Project Jennifer M. Martin, Ph.D. University of Colorado, MCDB Principal Investigator PHS 398 (Rev. 4/98) Page 2 E}B Number pages consecutively at the bottom throughout the application. Do not use suffixes such as 3a, 3b. CC Principal Investigator/Program Director (Last, first, middle): > Martin_ Jennifer M. Type the name of the principal investigator/program director at the top of each printed page and each continuation page. (For type specifications, see instructions on page 6.) RESEARCH GRANT TABLE OF CONTENTS Page Numbers Face Page .......................................................................................................................................................................................................................... Description,